Doses from Radiation Exposure

2 2nd October 2013 – Abu Dhabi

John Harrison Public Health England, UK

Committee 2 develops references models and data, including dose coefficients, for the assessment of exposures to radiation from both internal and external sources

- Large programme of work to replace all published dose coefficients following :

Publication 103 The 2007 Recommendations of the International Commission on Radiological Protection. Ann ICRP 37 (2-4) 2007

Committee 2 Remit

Societal benefit (not individual). No information, training or individual monitoring. Assessment of doses for compliance.

1 mSv or less

Individual direct or indirect benefit. Information, training and either individual monitoring or assessment.

Greater than 1 - 20 mSv

Exceptional situations. Benefit on a case-by-case basis. Information, training and individual monitoring of workers, assessment of public doses.

Greater than 20 - 100 mSv

CHARACTERISTICS

AND

REQUIREMENTS

BANDS OF

PROJECTED DOSE

Constraints, reference levels

Calculation of equivalent and effective dose

Effective dose, E

Mean absorbed dose, DT,Rin an organ or tissue

Equivalent dose, HT, in an organ or tissue

Radiation-weightingfactors, wR

Tissue-weightingfactors, wT

Biokinetic and Dosimetric Models

Intake byinhalation or ingestion

Publication 107 Nuclear Decay Data for Dosimetric Calculations. Ann ICRP 38 (3) 2008

Publication 110 Adult Reference Computational Phantoms. Ann ICRP 39 (32) 2009

Publication 116 Conversion Coefficients for Radiological Protection Quantities for External Radiation Exposures. Ann ICRP 40 (2-5) 2010

Publication 119 Compendium of Dose Coefficients based on ICRP Publication 60. Ann ICRP 41 (Supp1) 2012

Publication 123 Assessment of Radiation Exposure of Astronauts in Space. Ann ICRP 42 (4) 2013

C2 Publications since 2007

Phantoms and radiations transport calculations• Radiation Transport for Adult Phantoms (Adult SAFs)• Pediatric Reference Computational Phantoms + SAFs• Pregnant Female and Fetus Reference Computational

Phantoms + SAFsInternal dose coefficients •Occupational Intakes of Radionuclides, Parts 1 - 5• Internal Dose Coefficients for Members of the Public, Pts 1 & 2• In utero Internal Dose Coefficients for Maternal Intakes• Breast-feeding Infant Internal Dose Coefficients for Maternal

IntakesExternal dose conversion coefficients• External Dose Coefficients for Members of the PublicUse of Effective Dose

Planned publications

Stylized Phantoms Organ / body contours defined by 3D mathematical surface equations

Voxel Phantoms Organs and body tissues defined by groupingsof 3D arrays of tagged image volume elements

Hybrid Phantoms Organ / body contours defined by NURBS or polygon mesh surfaces

Phantom development

ICRP Publication 110Ann ICRP 39 (2) 2009

ICRP Adult Reference Computational Phantoms – Voxel Based

Newborn 1-year 5-year 10-year 15-year male 15-year female

ICRP Computational Phantoms – PediatricDeveloped using NURBS and PM Surface Modeling

Skeletal Dosimetry Models

ICRP C2 seminar. Rio de Janeiro , Brazil, 12 September 2012

OIR Part 1Introduction

OIR Part 2H, C, P, S, Ca, Fe, Co, Zn, Sr, Y, Zr, Nb, Mo, Tc

OIR Part 3Ru, Sb, Te, I, Cs, Ba, Ir, Pb, Bi, Po, Rn, Ra, Th, U

OIR Part 4Lanthanides and Actinides

OIR Part 5F, Na, Mg, K, Mg, Ni, Se, Mo, Tc, Ag

Occupational Intakes of Radionuclides

25475

ET1

ET2

BB

Albb

Extrathoracic airways

Bronchiolar

Bronchial

Alveolar interstitial

Human Respiratory Tract Model, Pub 66 (1994)

13

Cobalt-60 group

New HRTM

PuO2 group

ICRP 66

Kuempel

Al Retention: new data

Systemic model for Iodine

Former model (ICRP 1994)

OIR model

Inhaled particulate materials (5 µm AMAD aerosols)

Effective dose coefficients (Sv Bq-1)

57Co 58Co 60Co

Type F, cobalt nitrate, chloride 3.3E-10 1.4E-09 1.1E-08

Type M, all unspecified forms 1.0E-09 4.3E-09 2.7E-08

Type S, cobalt oxide, FAP, PSL 2.4E-09 6.6E-09 1.7E-07

Ingested materials

fA = 0.1, all chemical forms 2.4E-10 1.2E-09 7.6E-09

fA = 0.05, insoluble oxides 1.7E-10 9.8E-10 4.8E-09

OIR dose coefficients for cobalt

Bioassay data for 60Co : inhalation of 1 Bq Type M

Epidemiological approach

Ø Divide risk per WLMby risk per Sv= Sv per WLM

Dosimetric approach

Ø Calculate using models

Radon doses

USING 5 x 10-4 per WLM lung cancer risk

Workers 4.2 x 10-2 Sv-1 12 mSv WLM-1

Public 5.7 x 10-2 Sv-1 9 mSv WLM-1

Publication 65 values

Workers 5 mSv WLM-1

Public 4 mSv WLM-1

Epidemiological approach

Calculation for inhaled 222Rn + progeny

Effective dose, E

Mean absorbed dose, DT,Rto lung tissues, Gy

Equivalent dose, HT, to lungs, Sv

Radiation-weightingfactors, wR = 20

Tissue-weightingfactors, wT = 0.12

Biokinetic and Dosimetric Models

Intake byinhalation

25481

Air

Target cellnuclei

Sourceon surface

Geometric Model of Airway for Dosimetry

Alveolar-interstitium

Macrophages

Mucus gelCilia + Sol

Secretory cells

Basal cellsLaminapropria

Sub-epithelial tissue

25484

Bronchial (BB) Wall Dosimetry

• Aerosol characteristics

Ø Unattached fraction

Ø Size distribution

• Equilibrium factor

• Breathing rate

• Absorption of progeny

• Systemic biokinetics

Factors affecting dosimetric calculations

Ventilation

Radon gas

Radon gas

Radon progeny

Aerosolparticle

deposition

deposition

Formation of radon progeny aerosol

F=1Nuclide Bq m-3

222Rn gas 1.0218Po 1.0214Pb 1.0214Bi 1.0

F=0.3Nuclide Bq m-3

222Rn gas 1.0218Po 0.6214Pb 0.3214Bi 0.2

The value of F depends on the ventilation rate :

Indoors : F ≈ 0.4 Natural ventilation

Mines : F ≈ 0.2 Forced ventilation

F is a measure of the degree of dis-equilbrium between radon gas and its progeny

Equilibrium factor, F

0.1 1 10 100 1000 10000Particle diameter (nm)

Rel

ativ

e ac

tivity

AMTD = 0.9 nm σg =1.3

fp ≈ 10%

Unattached

Nucleation modeAMAD = 30 nm

Accumulation modeAMAD = 250 nm

Coarse modeAMAD = 5000 nm

Porstendörfer 2001, Marsh et al 2002

Activity size distribution for an indoor workplace

Mine E per WLM = 12 mSv

Lung wT = 0.12Relative detriment for lung = 0.286 all adults

E per WLM potentially = 29 mSv all adults

Lung tissue weighting cf. relative detriment- Effect on Rn-222 progeny dose

Lung apportionment factors

BB bb AIAF 1/3 1/3 1/3Mass (g) 1 2 1,100

Mine E per WLM = 12 mSvUsing average lung dose = 0.6 mSv

Lung dose apportionment - Effect on Rn-222 progeny dose

John Harrison (Chairman) UKFrançois Paquet (Vice-Chairman) France

Wesley Bolch (Secretary) USA

Mike Bailey UK John Hunt BrazilVladimir Berkovski Ukraine Chan Hyeong Kim (S Korea)Luiz Bertelli USA Rich Leggett USADoug Chambers Canada Jizeng Ma ChinaMarina Degteva Russia Dietmar Noßke GermanyAkira Endo Japan Nina Petoussi-Henss Germany

Frank Wissmann Germany

Membership 2013 - 17

Task Groups of Committee 2

Ø TG 04 - Dose Calculations (DOCAL) Wes Bolch

Ø TG 21 – Internal Dosimetry (INDOS)François Paquet

Ø TG 79 – Effective DoseJohn Harrison

Ø TG 90 – Dose Coefficients for External Environmental Exposures

Nina Petoussi-Henss

Ø C2 has large programme of work to provide new dose coefficients

Ø Biokinetic and dosimetric modelling is world leading, with scientific as well as protection applications

Ø C2 leading in explaining use of Effective dose

Ø Strong interactions between committees, including C2 membership of Task Groups

Summary

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